5881 v 6L6gc in tremolux

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StrummersOfThunder
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5881 v 6L6gc in tremolux

Post by StrummersOfThunder »

Anyone tell me if it would be ok to drop in a matched set of say, 6l6gc into my tremolux 6g9-b all would be well?
It currently has 5881s.
Its fixed bias.

WOndering if that will deliver a bit more clean headroom/bass punch and make it a more live use capable surf amp?

Thaaaaaanks in advance

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Re: 5881 v 6L6 in tremolux

Post by RectifiedAmps »

Going from 5881s to 6L6GCs is generally fine, assuming you’re re-biasing after swapping. But I’m skeptical of any perceived differences since these days 5881s are almost identical to 6L6GCs and (assuming you actually get 2W more clean output) +2W will be a barely perceptible increase in volume, if at all.

But it’s an easy thing to try in any case and valve manufacturers are claiming they design them to sound different, so YMMV. If it’s too close in sound, you could always try KT66s.

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Re: 5881 v 6L6 in tremolux

Post by StrummersOfThunder »

RectifiedAmps wrote: Mon Jun 10, 2024 11:28 am Going from 5881s to 6L6GCs is generally fine, assuming you’re re-biasing after swapping. But I’m skeptical of any perceived differences since these days 5881s are almost identical to 6L6GCs and (assuming you actually get 2W more clean output) +2W will be a barely perceptible increase in volume, if at all.

But it’s an easy thing to try in any case and valve manufacturers are claiming they design them to sound different, so YMMV. If it’s too close in sound, you could always try KT66s.
Interesting
I feel another tone shootout coming on...

Still a bit at sea with biasing. It does have a pot but I dont have bias probes. I could learn how to do the other ways. I should learn.
What would your approach be if you were a simple multimeter man like me.

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Re: 5881 v 6L6gc in tremolux

Post by RectifiedAmps »

Measure the DC resistance from the OT CT (usually a red wire) to pin 3 of each 5881 socket, with the amp off- write those values down. Then fire up the amp up, measure the voltage to ground at pin 3, then the voltage drop from pin 3 to the CT. Divide the voltage drop by the DC resistance and multiply by the voltage to ground and you get watts dissipated.

To adjust bias, keeping measuring from CT to one of the sockets- pin 3 while you tweak the bias potentiometer, until you get to where you want to be, wattage wise. You can assume the anode voltage won’t change much under slightly different biasing, but you can re-measure it at the end just to be sure.

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Re: 5881 v 6L6gc in tremolux

Post by StrummersOfThunder »

RectifiedAmps wrote: Mon Jun 10, 2024 11:53 am Measure the DC resistance from the OT CT (usually a red wire) to pin 3 of each 5881 socket, with the amp off- write those values down. Then fire up the amp up, measure the voltage to ground at pin 3, then the voltage drop from pin 3 to the CT. Divide the voltage drop by the DC resistance and multiply by the voltage to ground and you get watts dissipated.

To adjust bias, keeping measuring from CT to one of the sockets- pin 3 while you tweak the bias potentiometer, until you get to where you want to be, wattage wise. You can assume the anode voltage won’t change much under slightly different biasing, but you can re-measure it at the end just to be sure.
Legend !

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Re: 5881 v 6L6gc in tremolux

Post by StrummersOfThunder »

RectifiedAmps wrote: Mon Jun 10, 2024 11:53 am Measure the DC resistance from the OT CT (usually a red wire) to pin 3 of each 5881 socket, with the amp off- write those values down. Then fire up the amp up, measure the voltage to ground at pin 3, then the voltage drop from pin 3 to the CT. Divide the voltage drop by the DC resistance and multiply by the voltage to ground and you get watts dissipated.

To adjust bias, keeping measuring from CT to one of the sockets- pin 3 while you tweak the bias potentiometer, until you get to where you want to be, wattage wise. You can assume the anode voltage won’t change much under slightly different biasing, but you can re-measure it at the end just to be sure.
This really is a much easier instructional than ive found else where.

Here is the chassis btw
https://www.nzguitars.com/forum/viewtop ... b+tremolux

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